Relative water content and electrolyte leakage of cherry and plum leaves under osmotic stress

Absract. One of the modern tasks of breeding today is the search for promising vrieties of fruit crops characterized by high adaptation and production potential. Studies of perennial woody plants are complicated by a long life cycle of tree and labor intensity of setting up model experiments. This work presents the results of assessing the physiological state of cherry (Hodosa, Krasnodarskaya sladkaya, Tamaris, Timati) and plum (Milena, Podruga, Jo-jo) vaireties under controlled conditions of osmotic stress simulating artificial drought. A 15 % solution of sorbitol and a 5 % solution of polyethylene glycol (PEG) were used as osmotically active compounds. In the selected leaf samples, under and without stress conditions, the relative water content (RWC) and the level of electrolyte leakage (EL) were determined during the summer period of 2023-2024 in the hottest summer months – July and August. It was found that the most optimal variant of the model experiment was short-term using of PEG. Plum varieties were more susceptible to this stress factor, with maximum EL values about ~65 %. For cherry, the EL values did not exceed 44 %. The RWC values decreased on average after stress by 8–25 % for cherry plants and by 3–23 % for plums. During the two years of the study, plum varieties Podruga and Milena had a lower adaptive potential to osmotic stress, which physiological parameters changing by 1.3–5.3 times. Cherry varieties were characterized by a smaller difference between the control and stress variants, among them, the Krasnodarskaya sladkaya variety was more resistant, with the maximum variability of parameters not exceeding 2.5 times. Thus, the use of the experimental model makes it possible to quickly assess fruit varieties for drought resistance. Key words: cherry, plum, osmotic stress, relative water content, electrolyte leakage.